The present invention relates to a method of regenerating an exhaust gas purification filter of an internal combustion engine using a vaporized liquid to be introduced into the exhaust gas flow. The present invention furthermore relates to a vaporizer for carrying out the method according to the invention.
In diesel engines or gasoline engines driven by a lean mixture (e.g. gasoline direct injection engines), suitable particulate filters are employed for the reduction of the particulate emissions. These particulate filters need to be regenerated from time to time by burning off the particles accumulated on the filter surface. To this end, an oxidation catalytic converter is connected upstream of the particulate filter, the oxidation catalytic converter generating, by oxidation of an oxidizable substance present in the exhaust gas, the heat required for burning off the soot particles.
For regeneration of a particulate filter, it is therefore necessary from time to time to enrich the exhaust gas with an oxidizable substance, usually fuel. In addition to post-injection into the combustion chamber of the engine, systems are known for this purpose that use an additional high pressure fuel injection valve which is arranged in the manifold area of the exhaust system. Further known are systems having a metering pump which feeds a particular amount of fuel from the tank or from a low pressure fuel pipe into a heating chamber of a vaporizer (vaporizer chamber), where the fuel is vaporized and subsequently introduced into the exhaust gas flow.
The vaporizer systems usually operate with one or more glow plugs which are arranged in a vaporizer chamber to heat up and vaporize the fuel supplied. In the process, however, substances will become attached on a surface of the glow plug, which may result in a so-called “coking.” Such coking appears to a particularly great extent when biodiesel is used.